Question

某商品的进价为每件40元，售价为每件50元，每个月可卖出210件．如果每件商品的售价每上涨1元，则每个月少卖10件．当每件商品的售价定为多少元时，每个月的利润恰为2200元？

Answer 1

解法一：设每件商品的售价上涨x元，

(210－10x)(50＋x－40)＝2200··································································· 4分

解得x₁ ＝1，x₂＝10，··············································································· 6分

∴当x＝1时，50＋x＝51，当x＝10时，50＋x＝60；······························· 7分

解法二：设每件商品的售价为x元，

[210－10(x－50)] (x－40)＝2200································································ 4分

解得x₁ ＝51，x₂＝60，············································································· 7分

答：当每件商品的售价定为51或60元时，每个月的利润恰为2200元．··· 8分